1. Field of the Invention
This invention relates to a device for accelerating, and thereby imparting velocity and momentum to a fluid, especially to air, through the use of ions and electrical fields.
2. Description of the Related Art
A number of patents (see, e.g., U.S. Pat. Nos. 4,210,847 and 4,231,766) have recognized the fact that ions may be generated by an electrode (termed the xe2x80x9ccorona electrodexe2x80x9d), attracted (and, therefore, accelerated) toward another electrode (termed the xe2x80x9cattracting electrodexe2x80x9d), and impart momentum, directed toward the attracting electrode, to surrounding air molecules through collisions with such molecules.
The corona electrode must either have a sharp edge or be small in size, such as a thin wire, in order to create a corona discharge and thereby produce in the surrounding air ions of the air molecules. Such ions have the same electrical polarity as does the corona electrode.
Any other configuration of corona electrodes and other electrodes where the potential differences between the electrodes are such that ion-generating corona discharge occurs at the corona electrodes may be used for ion generation and consequent fluid acceleration.
When the ions collide with other air molecules, not only do such ions impart momentum to such air molecules, but the ions also transfer some of their excess electric charge to these other air molecules, thereby creating additional molecules that are attracted toward the attracting electrode. These combined effects cause the so-called electric wind.
However, because a small number of ions are generated by the corona electrode in comparison to the number of air molecules which are in the vicinity of the corona electrode, the ions in the present electric wind generators must be given initial high velocities in order to move the surrounding air. To date, even these high initial ionic velocities have not produced significant speeds of air movement. And, even worse, such high ionic velocities cause such excitation of surrounding air molecules that substantial quantities of ozone and nitrogen oxides, all of which have. well-known detrimental environmental effects, are produced.
Presently, no invention has even attained significant speeds of air movement, let alone doing so without generating undesirable quantities of ozone and nitrogen oxides.
Three patents, viz., U.S. Pat. Nos. 3,638,058; 4,380,720; and 5,077,500, have, however, employed on a rudimentary level some of the techniques which have enabled the present inventors to achieve significant speeds of air movement and to do so without generating undesirable quantities of ozone and nitrogen oxides.
U.S. Pat. No. 5,077,500, in order to ensure that all corona electrodes xe2x80x9cwork under mutually the same conditions and will thus all engender mutually the same corona discharge,xe2x80x9d uses other electrodes to shield the corona electrodes from the walls of the duct (in which the device of that patent is to be installed) and from other corona electrodes. These other electrodes, according to lines 59 through 60 in column 3 of the patent, xe2x80x9c. . . will not take up any corona current . . . xe2x80x9d
Also, U.S. Pat. No. 4,380,720 employs multiple stages, each consisting of pairs of a corona electrode and an attracting electrode, so that the air molecules which have been accelerated to a given speed by one stage will be further accelerated to an even greater speed by the subsequent stage. U.S. Pat. No. 4,380,720 does not, however, recognize the need to neutralize substantially all ions and other electrically charged particles, such as dust, prior to their approaching the corona electrode of the subsequent stage in order to avoid having such ions and particles repelled by that corona electrode in an upstream direction, i.e., the direction opposite to the velocity produced by the attracting electrode of the previous stage.
And U.S. Pat. No. 5,077,500, on lines 25 through 29 of column 1, states, xe2x80x9cThe air ions migrate rapidly from the corona electrode to the target electrode, under the influence of the electric field, and relinquish their electric charge to the target electrode and return to electrically neutral air molecules.xe2x80x9d The fact that the target electrode is not, however, so effective as to neutralize substantially all of the air ions is apparent from the discussion of ion current between the corona electrode K and the surfaces 4, which discussion is located on lines 15 through 27 in column 4.
Similarly, U.S. Pat. No. 3,638,058 provides, on line 66 of column 1 through line 13 of column 2, xe2x80x9c. . . it can be seen that with a high DC voltage impressed between cathode point 12 and ring anode 18, an electrostatic field will result causing a corona discharge region surrounding point 14. This corona discharge region will ionize the air molecules in proximity to point 14 which, being charged particles of the same polarity as the cathode, will, in turn, be attracted toward ring anode 18 which will also act as a focusing anode. The accelerated ions will impart kinetic energy to neutral air molecules by repeated collisions and attachment. Neutral air molecules thus accelerated, constitute the useful mechanical output of the ion wind generator. The majority of ions, however, will end their usefulness upon reaching the ring 18 where they fan out radially and collide with the ring producing anode current. A small portion of the ions will possess sufficient kinetic energy to continue on through the ring along with the neutral particles. These result in a slight loss of efficiency because they tend to be drawn back to the anode. The same theory will apply for cathode 13 and anode 17. Since opposite polarities are impressed on each cathode-anode pair, their exiting airstreams will contain oppositely charged ions which will merge and neutralize; i.e., being of opposite polarity, the ions will attract each other and be neutralized by recombination.xe2x80x9d It is, however, not clear that substantially all ions which escape the electrodes will merge because many ions emerging from the anode on the left are likely to have such momentum toward the left that the electrical attraction for ions emerging from the anode on the right with momentum toward the right is insufficent to overcome such opposite momenta. Furthermore, the distance required for such recombination as does occur is very probably so great that it would be a detriment to using multiple stages to provide increased speed to the air.
The present Electrostatic Fluid Accelerator employs two fundamental techniques to achieve significant speeds in the fluid flow, which can be virtually any fluid but is most often air, and which will not produce substantial undesired ozone and nitrogen oxides when the fluid is air.
First, to accelerate the fluid molecules significantly without having to impart high velocities to the ions, many ions are created within a given area so that there is a high density, or pressure, of ions. This is achieved by placing a multiplicity of corona electrodes close to one another. The corona electrodes can be placed near one another because they are electrically shielded from one another by exciting electrodes which have a potential difference, compared to the corona electrodes, adequate to generate a corona discharge. An exciting electrode is placed between adjacent corona electrodes and, thus, across the intended direction of flow for the fluid molecules.
In order to cause ions to create fluid flow, either the exciting electrode must be asymmetrically located between the adjacent corona electrodes (in order to create an asymmetrically shaped electric field that, unlike a symmetrical field, will force ions in a preferred direction) or there must be an accelerating electrode.
Preferably, in the case of an accelerating electrode, such accelerating electrode is an attracting electrode placed downstream from the corona electrodes in order to cause the ions to move in the intended direction. The electric polarity of the attracting electrode is opposite to that of the corona electrode.
It has, however, been experimentally determined that, when the corona electrodes are close to one another, if the electric potential of the exciting electrode is between that of the of the corona electrode and that of the attracting electrode, as in the case with respect to U.S. Pat. No. 5,077,500, the rate of fluid flow decreases. Indeed, when the electric potential of the exciting electrodes is the same as that of the corona electrode, no fluid flow occurs. This effect results from the fact that the electric field strength between the exciting electrode and the corona electrodes is not adequate to cause a corona discharge and produce ions; the corona discharge between the corona electrode and the attracting electrode is suppressed; and the consequent lower density of ions is inadequate to produce the desired flow of fluid, or, as explained above, any flow at all when the electric potential of the exciting electrodes is the same as that of the corona electrode. Furthermore, when the corona electrodes are placed close together in order to increase the density of ions, as described above, the electric field between the corona electrodes and the exciting electrodes influences the electric field between the corona electrodes and the attracting electrode. Thus, to achieve desirable flow rates, it is preferable to maintain the electric field strength between the exciting electrodes and the corona electrodes at a level that will produce a corona discharge and, consequently, a current flow from the corona electrodes to the exciting electrodes.
Yet, since the rate of fluid flow can be controlled by varying the electric field strength between the exciting electrode and the corona electrodes and since such electric field strength can be adjusted by varying the electric potential of the exciting electrode, the electric potential of the exciting electrodes can be varied in order to control the flow rate of the fluid with less expenditure of energy than when this is accomplished by controlling the potential of the attracting electrode.
Optionally, as suggested above, rather than using an attracting electrode as the accelerating electrode, a repelling electrode can be placed upstream from the corona electrode. The electrical polarity of the repelling electrode is the same as that of the corona electrode. From a repelling electrode, however, there is no corona discharge.
Second, in order to achieve the greatest flow of fluid, multiple stages of corona discharge devices are used with a collecting electrode between each stage. The collecting electrode has opposite electrical polarity to that of the corona electrodes. The collecting electrode is designed to preclude substantially all ions and other electrically charged particles from passing to the next stage and, therefore, being repelled by the corona electrodes of the next stage, which repulsion would retard the rate of fluid flow. The corona discharge device can be any such device that is known in the art but is preferably one utilizing the construction discussed above for increasing the density of ions.
A further optional technique for maximizing the density of ions is having a high-voltage power supply with a variable maximum voltage that depends on the corona current, which is defined as the total current from the corona electrode to any other electrode. The output voltage of the high-voltage power supply is inversely proportional to the corona current. Therefore, the voltage applied to the corona electrodes is reduced sufficiently, when the corona current indicates that a breakdown is imminent, that such breakdown is precluded. Without this option, the voltage between the corona electrodes and the other electrodes (except, of course, repelling electrodes, where no corona discharge is desired) must be manually maintained between the corona inception voltage and the breakdown voltage to have a sufficient electric field strength to create a corona discharge between the corona electrodes and the other electrodes without causing a spark-producing breakdown that would preclude the creation of the desired ions. The closer the voltage between such electrodes approaches, without actually attaining, the breakdown voltage, however, the greater will be the density of the ions that are generated.
The voltage applied to any electrode other than the corona electrode can, furthermore, also be used to control the direction of movement of the ions and, therefore, of the fluid. If desired, electrodes may be introduced for this purpose alone.